Aluminum alloy having a nano-complex phase

ABSTRACT

An aluminum alloy includes manganese of about 1.1% to about 7.0% by weight, magnesium of about 0.1% to about 6.0% by weight, scandium of about 0.01% to about 1.5% by weight and the balance is essentially aluminum. Alloying elements of scandium, manganese and magnesium are added to form a columnar grain structure with a nano-complex phase in the aluminum alloy. Accordingly, the aluminum alloy has a high degree of physical and mechanical properties.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to an aluminum alloy having a nano-complexphase. More particularly, the present invention relates to the aluminumalloy of Mn—Mg—Al that contains a predetermined amount of scandium (Sc)so as to facilitate formation of a columnar grain structure in thealuminum alloy with the nano-complex phase.

2. Description of the Related Art

Throughout the history of aluminum, various aluminum alloys have beenmade. Currently there are over 400 wrought aluminum and wrought aluminumalloys registered with the Aluminum Association. Aluminum alloys can becategorized into a number of groups based on the particular material'scharacteristics such as its ability to respond to thermal and mechanicaltreatment and the principal alloying element added to the aluminumalloy. The wrought aluminum alloys has a system of identification whichis a 4-digit system known as the 4-digit wrought aluminum identificationsystem.

In the 4-digit wrought aluminum identification system, the first digit(Xxxx) indicates the principal alloying element, which has been added tothe aluminum alloy and is often used to describe the aluminum alloyseries, i.e. 1000 series, 2000 series, 3000 series, up to 8000 series(see Table 1). The second digit (xXxx), if different from 0, indicates amodification of the specific alloy as well as modification times from 1to 9, and the third and fourth digits (xxXX) are arbitrary numbers givento identify a specific alloy in the series. For example, the third andfourth digits (xxXX) in the past are registered with Aluminum Company ofAmerica (Alcoa).

TABLE 1 Wrought Aluminum Alloy Designation System Alloy Series PrincipalAlloying Element 10XX 99.0% Minimum Aluminum 20XX Copper 30XX Manganese40XX Silicon 50XX Magnesium 60XX Magnesium and Silicon 70XX Zinc 80XXOther Elements 90XX New Alloy

In general, aluminum alloys are divided into two groups of heattreatable alloy and non-heat treatable alloy. The 20XX series, 40XXseries, 60XX series and 70XX series are heat treatable aluminum alloys;the 10XX series, 30XX series and 50XX series non-heat treatable aluminumalloys. The heat treatable aluminum alloys acquire their optimummechanical properties through a process of thermal treatment. The heattreatable aluminum alloy can be designed to have a higher degree ofhardness or tensile strength by means of the process of precipitationhardening heat treatment. By way of example, 7075-type aluminum alloy istreated at a temperature in a range of about 115 degrees centigrade toabout 125 degrees centigrade for 22 hours to 26hours.

TABLE 2 Mechanical Properties of Aluminum Alloy Tensile YieldingStrength Alloy Series Strength (kg/mm²) (kg/mm²) Elongation (%) 10805.5–9.5 1.5 30.0 2014 42.0 25.0 14.0 3005 20.0–25.0 17.0  2.0 305224.0–31.0 18.0 3.0–10.0 6061 30.0 25.0 10.0 7075 54.0 48.0  8.0

An aluminum-scandium alloy, as described in U.S. Pat. No. 5,597,529,entitled “ALUMINUM-SCANDIUM ALLOYS,” is directed to a modification ofAluminum Association alloy 6061 which has a composition of (0.4-0.8),Si-0.7 Fe-(0.15-0.4) Cu-0.15 Mn-(0.8-1.2) Mg-(0.04-0.35) Cr-0.25 Zn-0.15Ti. The modified alloy essentially removes chromium from the 6061 alloyand adds scandium in its place to obtain enhanced properties. Thismodified alloy generally comprises about (0.2-1.8) Si-(0.2-0.8)Mn-(0.4-1.4) Mg-(0.02-10.0) Sc, and is substantially free of chromium.

Another aluminum-scandium alloy described in U.S. Pat. No. 5,597,529 isfurther directed to a modification of Aluminum Association alloy 2319which has a composition of 0.2 Si-0.3 Fe-(5.8-6.8) Cu-(0.2-0.4) Mn-0.02Mg-0.1 Zn-(0.05-0.15) V-(0.1-0.25) Zr-(0.1-0.2) Ti. The modified alloyessentially adds scandium to the 2319 alloy to obtain enhancedproperties. This modified alloy generally comprises about (2.0-10.0)Cu-(0.02-10.0) Sc.

Another aluminum-scandium alloy described in U.S. Pat. No. 5,597,529 isfurther directed to a modification of Aluminum Association alloy 5356which has a composition of 0.25 Si-0.4 Fe-0.1 Cu-(0.05-0.2) Mn-(4.5-5.5)Mg-(0.05-0.2) Cr-0.1 Zn-(0.06-0.2) Ti. The modified alloy essentiallyadds scandium to the 5356 alloy to obtain enhanced properties. Thismodified alloy generally comprises about (2.7-6.0) Mg-(0.02-10.0) Sc.

Another aluminum-scandium alloy described in U.S. Pat. No. 5,597,529 isfurther directed to a modification of Aluminum Association alloy 4043which has a composition of (4.5-6.0) Si-0.8. Fe-0.3 Cu-0.05 Mn-0.05Mg-0.1 Zn-0.2 Ti. The modified alloy essentially adds scandium to the4043 alloy to obtain enhanced properties. The modified alloy generallycomprises about (3.0-15.0) Si-(0.02-10.0) Sc.

As mentioned above, the modified alloy may add a greater amount ofscandium to alloy 6061, alloy 2319, alloy 5356 and alloy 4043. However,scandium is a high-cost metal. While the addition of scandium to thealloy may have an effect on the very high degree of mechanical property,it is generally considered to be too expensive for use as an ordinaryalloyed material. Hence, there is a need for reducing the amount ofscandium and increasing the amount of low-cost metals for achieving thealloy at a relatively reasonable cost.

Still, there is a need for forming a columnar grain structure in thealuminum alloy such that the mechanical strength of the aluminum alloycan be increased without being treated in the process of heat treatment.To this end, the principal alloying elements added to the aluminum alloymay be changed or adjusted for gaining a higher degree of mechanicalstrength.

As is described in greater detail below, the present invention intendsto provide an aluminum alloy having a nano-complex phase through theaddition of alloying elements. The aluminum alloy adds a small amount ofscandium and a greater amount of low-cost metal which can facilitateformation of the nano-complex phase. The addition of the alloyingelements may produce a uniform columnar grain structure in the aluminumalloy in precipitation during solidification in such a way as tomitigate and overcome the above problem.

SUMMARY OF THE INVENTION

The primary objective of this invention is to provide an aluminum alloyhaving a nano-complex phase, wherein predetermined amounts of scandium(Sc), manganese (Mn) and magnesium (Mg) are added to the aluminum alloyto form a columnar grain structure with the nano-complex phase.Accordingly, the mechanism properties of the aluminum alloy are improvedor enhanced.

The secondary objective of this invention is to provide the aluminumalloy having the nano-complex phase, wherein predetermined amounts ofscandium (Sc), manganese (Mn) and magnesium (Mg) are added to thealuminum alloy to form the nano-complex phase. The nano-complex phase ofthe aluminum alloy may be treated through a process of heat treatmentfor adjusting a growth orientation along its longitudinal direction.Accordingly, the mechanism properties of the aluminum alloy are furtherimproved or enhanced.

Another objective of this invention is to provide the aluminum alloyhaving the nano-complex phase, wherein the aluminum alloy adds a smallamount of scandium and a greater amount of manganese. Accordingly, thealuminum alloy is achieved at a relatively reasonable cost.

The aluminum alloy in accordance with an aspect of the present inventionincludes manganese of about 1.1% to about 7.0% by weight, magnesium ofabout 0.1% to about 6.0% by weight, scandium of about 0.01% to about1.5% by weight and the balance is essentially aluminum. Alloyingelements of scandium, manganese and magnesium are added to form acolumnar grain structure with a nano-complex phase in the aluminumalloy. Accordingly, the aluminum alloy has a high degree of physical andmechanical properties.

In a separate aspect of the present invention, the aluminum alloyincludes silicon of about 0.01% to about 0.50% by weight, iron of about0.01% to about 0.10% by weight, copper of about 0.01% to about 0.50% byweight, chromium of about 0.01% to about 0.50% by weight, nickel ofabout 0.01% to about 0.50% by weight and mixtures thereof.

In a further separate aspect of the present invention, the aluminumalloy includes titanium of about 0.01% to about 0.10% by weight,vanadium of about 0.01% to about 0.10% by weight, cobalt of about 0.01%to about 0.10% by weight, zinc of about 0.01% to about 0.10% by weight,zirconium of about 0.01% to about 0.10% by weight, niobium of about0.01% to about 0.10% by weight, molybdenum of about 0.01% to about 0.10%by weight, yttrium of about 0.01% to about 0.10% by weight, tungsten ofabout 0.01% to about 0.10% by weight, lanthanum of about 0.01% to about0.10% by weight and mixtures thereof.

In a yet further separate aspect of the present invention, the columnargrain structure has a diameter ranging from 40 μm to 100 μm.

In a yet further separate aspect of the present invention, the columnargrain structure has a length ranging from 0.2 μm to 1.0 μm.

In a yet further separate aspect of the present invention, thenano-complex phase has a growth orientation substantially extendingalong its longitudinal direction.

In a yet further separate aspect of the present invention, the aluminumalloy is used to manufacture golf club heads, golf club shafts or otherclub head members.

Further scope of the applicability of the present invention will becomeapparent from the detailed description given. hereinafter. However, itshould be understood that the detailed description and specificexamples, while indicating preferred embodiments of the invention, aregiven by way of illustration only, since various will become apparent tothose skilled in the art from this detailed description.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention will become more fully understood from thedetailed description given hereinbelow and the accompanying drawingswhich are given by way of illustration only, and thus are not limitativeof the present invention, and wherein:

FIG. 1 is a photomicrograph of a cross section of an aluminum alloyhaving a nano-complex phase in accordance with a preferred embodiment ofthe present invention, with a magnification of 15,000 times,illustrating a columnar grain structure (encircled portion) along alongitudinal direction thereof; and

FIG. 2 is a photomicrograph of a cross section of the aluminum alloyhaving the nano-complex phase in accordance with the preferredembodiment of the present invention, with a magnification of 15,000times, illustrating a columnar grain structure (encircled portion) alonga cross-sectional direction thereof.

DETAILED DESCRIPTION OF THE INVENTION

An aluminum alloy having a nano-complex phase in accordance with apreferred embodiment of the present invention includes major elements ofAluminum (Al), manganese (Mn) and magnesium (Mg). In the preferredembodiment, the aluminum alloy includes manganese of about 1.1% to about7.0% by weight, magnesium of about 0.1% to about 6.0% by weight and thebalance is essentially aluminum. The aluminum alloy acquires amechanical property of toughness according to an amount of aluminumaddition. The addition of manganese enhances the aluminum alloy topossess a high degree of hardness. Also, the addition of magnesiumfurther enhances the aluminum alloy to possess a high degree of strengthand corrosion resistance.

Referring now to FIGS. 1 and 2, the aluminum alloy in accordance withthe preferred embodiment of the present invention further includesscandium of about 0.01% to about 1.5% by weight. The addition ofscandium may produce uniform distribution and nucleation of columnargrain structures in the aluminum alloy in precipitation duringsolidification, as best shown in encircled portions in FIGS. 1 and 2.The nano-complex phase is formed in the uniform columnar grainstructure. The columnar grain structure has a diameter ranging from 40nm to 100 nm, and a length ranging from 0.2 μm to 1.0 μm that constitutethe nano-complex phase. It would be desire that the amount of manganeseranging from 1.1 wt % to 7.0 wt % can facilitate formation of thecolumnar grain structure in the aluminum alloy.

In a preferred embodiment, when solidified, the aluminum alloy istreated in a heat treatment process so as to adjust major growthorientations of the nano-complex phase of the aluminum alloysubstantially extending along their longitudinal directions. It would bedesire that the heat treatment process can ensure the diameters of thegrains within the nano sizes. Advantageously, the heat treatment cansignificantly increase physical and mechanical properties of themodified aluminum alloy.

In addition, the modified aluminum alloy of the present invention mayfurther include alloying elements, silicon (Si), iron (Fe), copper (Cu),chromium (Cr), nickel (Ni) and mixtures for example, without departingfrom the scope and spirit of the present invention. In a preferredembodiment, the aluminum alloy includes silicon of about 0.01% to about0.50% by weight, iron of about 0.01% to about 0.10% by weight, copper ofabout 0.01% to about 0.50% by weight, chromium of about 0.01% to about0.50% by weight, nickel of about 0.01% to about 0.50% by weight andmixtures thereof. Consequently, the additions of these alloying elementscan further enhance physical and mechanical properties of the modifiedaluminum alloy.

In addition to the foregoing, the modified aluminum alloy of the presentinvention may further include other alloying elements, titanium (Ti),vanadium (V), cobalt (Co), zinc (Zn), zirconium (Zr), niobium (Nb),molybdenum (Mo), yttrium (Y), tungsten (W), lanthanum (La) and mixturesfor example, without departing from the scope and spirit of the presentinvention. In a preferred embodiment, the aluminum alloy includestitanium of about 0.01% to about 0.10% by weight, vanadium of about0.01% to about 0.10% by weight, cobalt of about 0.01% to about 0.10% byweight, zinc of about 0.01% to about 0.10% by weight, zirconium of about0.01% to about 0.10% by weight, niobium of about 0.01% to about 0.10% byweight, molybdenum of about 0.01% to about 0.10% by. weight, yttrium ofabout 0.01% to about 0.10% by weight, tungsten of about 0.01% to about0.10% by weight, lanthanum of about 0.01% to about 0.10% by weight andmixtures thereof. Consequently, the additions of these alloying elementscan further enhance physical and mechanical properties of the modifiedaluminum alloy.

The differences of mechanical properties between the modified aluminumalloy and the conventional aluminum alloys are set forth in Table 3. InTable 3, the mechanical properties typically include data of tensilestrength, yielding strength and elongation. The mechanical properties ofthe conventional aluminum alloys (representing three different alloys)and the modified aluminum alloy. of the present invention are compared,according to data in Table 3.

TABLE 3 Comparison Table for Mechanical Properties of the modifiedaluminum alloy and conventional aluminum alloys Mechanical PropertyTensile Strength Yielding Strength Elongation Alloy Type (ksi*) (ksi*)(%) Low-Carbon Steel 58 32 25 1025** A356 T6 40 30 6 A357 Cast O-T62 4535 3 Embodiment 57 42 9 *ksi = 10³ psi. **Hot Rolled Low-Carbon Steel.

In comparison with the conventional alloys of A356 T6 and A357 CastO-T62, the modified aluminum alloy of the present invention has asignificant increase in each of mechanical properties of tensilestrength, yielding strength and elongation, as can be seen from Table 3.In comparison with the conventional alloys of hot rolled low-carbonsteel (low-carbon steel 1025), the modified aluminum alloy of thepresent invention still has a significant increase in yielding strengtheven if there is a decrease in elongation. Furthermore, the tensilestrength of the modified aluminum alloy is similar to that of the hotrolled low-carbon steel (low-carbon steel 1025). The modified aluminumalloy, however, possesses an adequate degree of elongation due to theimprovement compared to the conventional aluminum alloy (A356 T6 andA357 Cast O-T62) These results indicate that the additions of therelatively smaller amount of scandium (0.01 wt % to 1.5 wt %) and therelatively greater amount of manganese (1.1 wt % to 7.0 wt %) improvethe mechanical properties of the modified aluminum alloy. Consequently,the modified aluminum alloy of the present invention is suitable formanufacturing sport equipments, such as golf club heads, golf clubshafts or other club head members (e.g. club weight members).

In FIGS. 1 and 2, two photomicrographs, with a magnification of 15,000times, of an aluminum alloy having a columnar grain structure (encircledportion) along longitudinal and cross-sectional directions thereof inaccordance with a preferred embodiment of the present invention areillustrated. It is apparent from FIGS. 1 and 2, the addition of thedesignated amount of scandium and magnesium may produce uniformdistribution and nucleation of columnar grain structures in the aluminumalloy in precipitation during solidification. Subsequently, the modifiedaluminum alloy may be treated through a process of heat treatment foradjusting a growth orientation along its longitudinal direction suchthat diameters of the grain structure can be maintained within nanosizes. Furthermore, the aluminum alloy may be modified to maintainmechanical properties similar to those of the low-carbon steel even ifthe elongation of the modified aluminum alloy is lower than that oflow-carbon steel. Nonetheless, the elongation of the modified aluminumalloy is still greater than that of alloy A356 T6 or alloy A357 CastO-T62 such that the modified aluminum alloy is suitable formanufacturing golf club heads, golf club shafts or other club headmembers. Yet furthermore, the modified aluminum alloy possesses agreater degree of corrosion resistance.

The compositions, the nano-complex phase and manufacturing cost of themodified aluminum alloy and the conventional aluminum alloys are setforth in Table 4. In Table 4, the compositions of the aluminum alloyinclude scandium, manganese and magnesium.

TABLE 4 Comparison Table for Compositions, Nano-Complex Phase andManufacturing Cost of Conventional Aluminum Alloy and Modified AluminumAlloy of the Present Invention Nano- Sc Mn Complex Alloy Type (wt %)*(wt %)** Mg (wt %) Phase Cost Modified Alloy <1.5% 1.1%–7.0% 0.1%–6.0%Excellent Low Conventional >1.5% <1.1% 0.1%–6.0% None High Alloy*high-cost metal **low-cost metal

The modified aluminum alloy adds a small amount of scandium and agreater amount of magnesium for facilitating formation of thenano-complex phase, as can be seen from Table 4. The conventionalaluminum alloy cannot produce a nano-complex phase due to the fact thatthe amount of magnesium is smaller than 1.1 wt %. In addition to this,the conventional aluminum alloy cannot reduce the manufacturing cost dueto the fact that the amount of scandium is greater than 1.5 wt %. In thepreferred embodiment, the modified aluminum alloy adds a smaller amountof scandium (i.e. smaller than 1.5 wt %) and a greater amount ofmagnesium (i.e. greater than 1.1 wt %). Advantageously, the modifiedaluminum alloy possesses improved mechanical properties and also reducesmanufacturing cost by using a greater amount of low-cost metal.

It will be apparent from the aforementioned discussions that theconventional aluminum alloy adds a smaller amount of magnesium thatcannot facilitate the formation of the nano-complex phase of scandium inthe aluminum alloy during solidification. Conversely, the modifiedaluminum alloy has an increase in the predetermined amount of magnesium(i.e. low-cost metal), a decrease in the predetermined amount ofscandium (i.e. high-cost metal) such that a columnar grain structure isformed in the nano-complex phase. Advantageously, such a modifiedaluminum alloy. possesses a high degree of mechanical properties andalso reduces the manufacturing cost.

Although the invention has been described in detail with reference toits presently preferred embodiment, it will be understood by one ofordinary skill in the art that various modifications can be made withoutdeparting from the spirit and the scope of the invention, as set forthin the appended claims.

1. An aluminum alloy having a nano-complex phase, comprising: manganeseof about 1.1% to about 7.0% by weight; magnesium of about 0.1% to about6.0% by weight; scandium of about 0.01% to about 1.5% by weight; and thebalance being essentially iron aluminum wherein additions of thescandium, the manganese and the magnesium produce a columnar grainstructure with the nano-complex phase in the aluminum alloy.
 2. Thealuminum alloy having the nano-complex phase as defined in claim 1,further comprising silicon of about 0.01% to about 0.50% by weight, ironof about 0.01% to about 0.10% by weight, copper of about 0.01% to about0.50% by weight, chromium of about 0.01% to about 0.50% by weight,nickel of about 0.01% to about 0.50% by weight and mixtures thereof. 3.The aluminum alloy having the nano-complex phase as defined in claim 1,further comprising titanium of about 0.01% to about 0.10% by weight,vanadium of about 0.01% to about 0.10% by weight, cobalt of about 0.01%to about 0.10% by weight, zinc of about 0.01% to about 0.10% by weight,zirconium of about 0.01% to about 0.10% by weight, niobium of about0.01% to about 0.10% by weight, molybdenum of about 0.01% to about 0.10%by weight, yttrium of about 0.01% to about 0.10% by weight, tungsten ofabout 0.01% to about 0.10% by weight, lanthanum of about 0.01% to about0.10% by weight and mixtures thereof.
 4. The aluminum alloy having thenano-complex phase as defined in claim 1, wherein the columnar grainstructure has a diameter ranging from 40 nm to 100 nm.
 5. The aluminumalloy having the nano-complex phase as defined in claim 1, wherein thecolumnar grain structure has a length ranging from 0.2 μm to 1.0 μm. 6.The aluminum alloy having the nano-complex phase as defined in claim 1,wherein the nano-complex phase has a growth orientation substantiallyextending along its longitudinal direction.
 7. The aluminum alloy havingthe nano-complex phase as defined in claim 1, wherein the aluminum alloyis used to manufacture golf club heads, golf club shafts or other clubhead members.